1. Field of the Invention
The present invention relates in general to automatic sizing devices for particulate or granular material and more specifically to such devices that include mesh sizing screens for separating various sized particles from one another.
2. Description of the Prior Art
Foreign matter in grain may comprise a substantial portion of the grain volume. For example, the amount of foreign matter in dry corn may be as much as 12% to 15% by weight. It is obviously desirable to remove this foreign matter from the grain in order to provide a more salable product. In addition, removal of foreign matter decreases grain freight costs because the volume of foreign matter removed will be replaced by grain, thereby resulting in more grain per cubic foot being shipped, an important economic factor when considering shipping costs and storage costs.
Foreign matter found in grain can be either material which is larger than the kernel, commonly referred to as "overs," or material smaller than the kernel, such as broken kernels, weed seed, sand, dirt, and dust, commonly referred to as "thru's." Numerous devices have been successfully used for eliminating "thru's" from the grain but there are few known devices for successfully removing "overs." However, due to certain shipping requirements, it is becoming increasingly important to remove the "overs" from grain. One such requirement is that corn shipped into the State of California must be passed over a one-half inch opening screen for removal of "overs" so that the corn qualifies for a European Corn Borer Certificate.
In the past, the removal of "overs," such as cobs, rocks, and husks has been accomplished by using a vibrating machine or a shaker device. However, such devices have an inherent deficiency in that they may be harmful to the concrete structures in which they are housed over long periods of time due to harmonic vibrations they produce. The present invention entirely eliminates the need for such shaking or vibrating operation and is much more economically constructed than prior art devices.